The present invention relates to fiber optic probe device for bodily implantation for physiologic measurements of body fluid components and, more particularly, to the physiologic measurement of oxygen and glucose in blood or tissue.
Physiologic oxygen and glucose measurements are important for many reasons. The advantages of optical measurements of blood oxygen saturation levels during certain medical procedures, such as cardiopulmonary bypass heart surgery, are apparent. Equally important are physiologic measurements of glucose in blood tissue or serum to indicate metabolic malfunctions such as diabetes. Fiber optic devices for measurement of blood oxygen saturation are well known. In U.S. Pat. No. 3,807,390 to Ostrowski et al there is disclosed a fiber optic catheter for monitoring blood oxygen saturation in a human blood stream, in vivo, by insertion of the catheter tip into the cardiovascular system of the living body.
In U.S. Pat. No. 3,542,662 to Hicks et al there is described a bioelectrode for use in the determination of glucose in blood and serum. In this patented device an enzyme reaction is coupled to an electrode process. A glucose electrode consisting of a membrane of immobilized glucose oxidase is described. When the enzyme electrode is placed in contact with a biological solution or tissue, the glucose and oxygen diffuse into the enzyme layer with a corresponding outward flow of hydrogen peroxide and gluconic acid. The relationship between the oxygen saturation level and the amount of gluconic acid and peroxide present in the system is then calculated and the amount of glucose ascertained.
In U.S. Pat. No. 4,201,222 to Haase there is disclosed an optical catheter, including a fiber optic bundle, adapted to be inserted into a blood vessel of a living body for measuring the partial pressure of oxygen gas in the blood stream. The catheter comprises a semipermeable wall member for excluding the entry therethrough of blood liquid while permitting passage of blood gases. The intensity of a reflected visible light beam entering the optical fiber bundle, when compared to the intensity of the incident beam, corresponds to the partial pressure of the oxygen gas in the blood stream.
The present invention relates to a fiber optical device for the in vitro physiological measurement of oxygen and glucose by means of chemical sensors employing luminescent quenching mechanisms. The oxygen quenching of flourescent compounds is disclosed in U.S. Pat. No. 3,612,866 to Stevens where an apparatus for measuring the oxygen content of liquids or gases is described. The indicator mechanism is based on the molecular luminescent quenching effect of gaseous oxygen on aromatic flourescent compounds. Additionally, Lubbers et al in U.S. Pat. No. 4,003,707 describes an optical device for measuring physiologic oxygen in which the indicator element is the flourescent dye, pyrene butyric acid, which is quenched by oxygen molecules during use. Each of these devices is complex and is unconcerned with the size of the measuring device and replacement of the dye indicator systems.
Peterson et al in U.S. Pat. No. 4,476,870 describes an implantable fiber optic PO.sub.2 biological probe comprising two strands of optical fiber terminating in a jacketed chemical indicator system. The indicator element contains a luminescent oxygen quenching dye, such as perylene dibutyrate, on an inorganic adsorbant support all packed in a tube, or envelope, of a gas permeable polymeric material. Light is introduced through one strand which light excites the jacketed dye to fluorescence. The flourescent and scattered light then exits through the other fiber optic strand to a measuring device to indicate the level of the oxygen quenching of the dye. While the Peterson et al device is both tiny and flexible for convenient bodily use, it suffers from the disadvantage that the adsorbed dye is ultimately lost through leaching into the fluid systems during use thereby requiring replacement of the entire structure.
Each of the above systems have advantages and disadvantages as applied to specific situations. In one or more of the systems, expensive and complex equipment is required especially in the case of glucose sensors. Moreover, even in the simple compact structures, such as that of Perterson et al, the optical system is integral and the total device must be replaced when the chemical sensor element becomes nonreusable. Therefore, there is significant interest in finding relatively simple physiological optical measuring devices in which the chemical sensor element is easily replaceable.